So, I brew 10 gallons and split them into five gallon fermenters. A couple of days ago, I did two starters for each fermenter, but ran out of time to properly cool them. That being said, when I pitched the starters, one fermenter had live yeast and it took off, while the other apparently had dead yeast and it did not. My question is, can I take wort from the fermenter that is fermenting and add it to the one that did not? If so, would I add the same amount of wort to it that was my starter size? In this case, that would be 1.27 liters.

SWAG
I have no facts to base this on but I don't believe there is as much yeast in 1.27 liters of fermenting wort as there would be from 1.27 liters of a starter. But there might be enough yeast in 1.27 liters of fermenting wort to make a fresh starter.

Even if you could make a starter with fermenting wort it would still take a day and that would be another day the sweet vulnerable wort would be exposed. If you have more yeast just pitch some or if a LHBS is close buy a pack of dry yeast and pitch into the brew bucket/carboy.

SWAG
I have no facts to base this on but I don't believe there is as much yeast in 1.27 liters of fermenting wort as there would be from 1.27 liters of a starter. But there might be enough yeast in 1.27 liters of fermenting wort to make a fresh starter.

Even if you could make a starter with fermenting wort it would still take a day and that would be another day the sweet vulnerable wort would be exposed. If you have more yeast just pitch some or if a LHBS is close buy a pack of dry yeast and pitch into the brew bucket/carboy.

I agree with this ^

You could indeed use 1.27L of your wort to make a starter, but it would likely take a few step-ups. That could take as long as a week or more, so buying more yeast or using dry yeast would be a better option..